Localization devices have been developed to assist surgeons in performing surgical procedures. Markers are attached to bones that are observable by a stereoscopic camera system connected to a data processing system that records the positions of the markers in space to establish a coordinate reference system relative to each bone. Additional markers are attached to tools used during the surgical procedures. Typically, these markers are removable so that one marker can be used with multiple tools as needed during a procedure. By tracking the marker associated with a tool, positional parameters associated with the tool can be tracked in the coordinate reference systems of the bones. A monitor displays a representation of the bones and the position of the tools in the coordinate reference systems of the bones for use in guiding a surgeon during surgical procedures. A description of one particular localization device is described in U.S. Pat. No. 6,385,475 to Cinquin et al., incorporated fully herein by reference.
Surgical procedures performed using a localization device are typically carried out in a number of sequential steps. For example, to make a cut in a bone, initially, a number of steps are performed using the localization device in order to establish a coordinate reference system and to determine the precise angle and depth of the cut to be made in the bone. The localization device is then used in a first navigation step to guide a surgeon in the placement of a cutting jig, which contains a cutting guide used to guide a saw in a cutting plane defined by the cutting guide. A removable marker attached to the cutting jig allows the localization device to track the cutting jig to obtain information for use in performing the first navigation step. Once the cutting jig is in place, it is secured to the bone with pins. After the cutting jig is secured, the removable marker is removed from the cutting jig for later attachment to tools used in subsequent navigation steps.
Often, during a procedure, it is desirable to record positional parameters associated with a tool at the end of a navigation step for post operative analysis. For example, when making a cut in a bone, it is desirable to record the angle of the cutting plane defined by the cutting guide of a cutting jig and the distance of the cutting plane from a reference point on the bone to determine if the cutting jig was positioned properly or to compare the positional parameters of the cutting jig to the positional parameters of cutting jigs in similar procedures and their roles in the success or failure of a procedure. Ideally, when a surgeon finishes a navigation step, prior to the removal of the marker from the tool being navigated, the surgeon provides an indication to the localization device that this step of the procedure is over, e.g., by depressing a foot switch coupled to the localization device. The localization device then records the positional parameters associated with the tool. Sometimes, however, the surgeon removes the marker prior to indicating that this step of the procedure is over. Thus, since the marker is no longer associated with the tool, the positional parameters recorded by the localization device will not represent the actual positional parameters associated with the tool. Hence, the recorded positional parameters will be useless.
A surgeon's primary focus during a procedure is the successful completion of that particular procedure. Thus, steps that are not critical to the success of the operation may be seen as burdensome to the surgeon. Therefore, the surgeon may neglect to perform inconvenient tasks such as indicating that a navigation step is over prior to removal of the marker from the tool being navigated if it is not critical to the present procedure and the only reason for doing so is the accumulation of data for post operative analysis.
Accordingly, a convenient method is needed that ensures navigated tool positional parameters are accurately recorded.